Field of the Invention and Related Art Statement
The present invention relates to a method of recording data on an optical card.
Optical cards have a memory capacity of several hundreds to ten thousands times larger than the presently used magnetic cards and do not have rewritable capability like optical disks. However, because the optical cards have a large memory capacity of 1 to 2 M bytes, they promise a wide range of applications including bankbooks for banking, portable maps, prepaid shopping card, and the like.
The optical cards may be roughly classified into a first type of optical card in which a single ID portion including the track address is provided only at one end of each respective tracks (hereinafter abbreviated to a single-side ID optical card), and a second type of optical card in which two ID portions are provided at both ends of each respective tracks (hereinafter abbreviated to a double-side ID optical card). The first type of optical card is disclosed in, for instance, the Japanese Patent Laid-Open Publication Kokai Sho 63-37876.
In case of using such optical cards, generally, an optical card is moved in a track direction which is parallel to tracks to perform data recording, data reproduction, and ID portion reading. An access to a desired track is performed by a combination of a coarse access and a track jump. In the coarse access, an optical head with an objective lens is totally moved in a direction perpendicular to the track direction by utilizing a linear driving mechanism and is positioned into a desired track by detecting the position of the optical head with respect to the optical card by means of a position detecting means. In the track jump, the objective lens in the optical head is moved over tracks one by one by using a tracking driver. The tracking driver usually serves to move the objective lens such that the light beam can always follow tracks on the optical card.
FIG. 1 shows a configuration of the single-side ID optical card. The optical card 1 has a record area 3 in which a plurality of parallel tracks 2 are provided. Each of the tracks 2 includes an ID portion 4 provided at one end of the track and a data portion 5. In the ID portion 4 a track address signal has been pre-recorded such that the track address signal can be correctly read out when the optical card 1 is scanned by a reading light beam in a correct direction, i.e. from right to left in FIG. 1.
Now a known method of recording data onto the optical card shown in FIG. 1 will be explained with reference to a flow chart illustrated in FIG. 2. After the reading light beam having a lower power has been accessed to a desired track by performing the coarse access and track jump, the light beam is moved into one end point S.sub.1 near the ID portion 4. Next, the optical card 1 is fed in the right hand direction in FIG. 1 to perform a blank check of the relevant track and the optical beam is positioned to the other end point S.sub.2 of the optical card 1. The blank check may be performed by checking a change in the reflectance of the optical card or by detecting a presence of a high frequency component of the read out signal. As the result of this blank checking, when it is detected that a desired sector in the track is in an unwritten condition, the optical card 1 is fed in the left hand direction in FIG. 1 to move the light beam from the point S.sub.2 to the point S.sub.1. Next, the optical card 1 is moved again in the right hand direction, and when the light beam is made incident upon a start point of the desired sector, the power of the light beam is increased to a recording power and at the same time the light beam is modulated in accordance with a data signal to be recorded in the relevant sector.
However, the conventional data recording method using the single-side ID optical card has a disadvantage in that the access time is liable to be long, because each time the blank check is performed, the optical card 1 is moved from the, point S.sub.1 to the point S.sub.2, these points being situated at opposite ends of the track. That is to say, even if a desired blank sector is a first sector viewed in the scanning direction, the optical card has to be moved into the other end point S.sub.2. It should be noted that in the double-side ID optical card, this could not be a disadvantage, because in this type of optical card, the data recording can be carried out in both moving directions of the optical card.